Embodiments of the present invention relate generally to telephones and more particularly to call blocking using, e.g., a caller ID device.
Caller Identification (hereinafter “caller ID”) is a feature provided by local phone companies that sends information from the telephone network to a telephone device between the first and second rings. The information that is sent varies and generally includes the calling telephone number and the name of the caller. This information is sent via the telephone line in a digital data packet that is usually Frequency Shift Keyed (hereinafter “FSK”) modulated. At the receiving telephone device the subscriber must be signed up for the caller ID service and must have a caller ID data receiver, i.e., a caller ID unit, connected to the telephone line in order to receive the digital data packet containing the caller ID information for the calling telephone device. The data receiver receives the FSK modulated digital data packet and provides a visual display of the information. In operation, the caller ID unit receives the FSK modulated digital data packet, demodulates it and converts the information into a stream of text characters that is then displayed, for example, on a liquid crystal display (LCD) provided either on the caller ID unit or which is integral to the telephone device itself. As discussed before, for an incoming call, the caller ID information that is displayed at the receiving side can include the name and number of the calling party among other types of information. The central office must have “caller ID capability” and the service must be enabled within the central office of the local telephone exchange. If, however, the central office does not have caller ID capability, the called party will receive a variety of messages including, for example, “out of area.”
Among the information that is displayed on the caller ID unit is the originating telephone number and the name listed in the directory under that number. In other words, the name that is displayed is the name that the telephone company has entered into a database and believes to be that of its customer. The number in the local central office database also aids another database lookup and thus associates the name in the directory with the number from where the call originates. The calling party's name and number information is transmitted through the central office and the telecommunication network and ultimately is displayed at the caller ID unit or on the telephone device itself. As discussed hereinbefore, such caller ID information is generally transmitted and displayed between the first and second rings. For caller ID to work properly in a telecommunication environment, the telecommunication network switches must be supported by Common Channel Signaling (CCS) and the party initiating the call must originate it from a single-channel line, a multi-channel trunk line with ANI/Calling Party ID. Further, if the originating line or caller blocks the transmission of the caller ID information, the receiving party will not be able to view the information or the receiving device will display, for example, “ANONYMOUS,” “NOT AVAILABLE” or “PRIVATE CALLER.”